Starship flight 4: a soft landing in the Indian Ocean

On 6 June, from the flat scrubland of Boca Chica in south Texas, Starship, the largest rocket ever built, lifted off on its fourth test flight, and about an hour later a vehicle that had been higher than most of the atmosphere was back in the sea in one piece. It was the first time either half of the rocket had survived the trip. The booster, Super Heavy, came down in the Gulf of Mexico roughly seven minutes after launch, firing its engines for the first landing burn of its career and settling into the water as gently as the company could have asked. The ship above it coasted through space for some forty minutes, then turned for home, met the atmosphere off the coast of northern Australia, and proved that it could survive the violence of reentry as well.

The reentry was not clean. Thirty-two of the thirty-three Raptor engines lit on the way up, and one of the ship’s steering flaps burned nearly through as it fell, so that the live view from the onboard camera, relayed by Starlink, showed pieces of the vehicle streaming past the lens before it cracked. SpaceX had deliberately removed two heat-shield tiles before the flight to measure what the bare steel underneath would tolerate, and the ship lost many more tiles than that on its way down. The engineers on the broadcast sounded like they were willing it down. When the ship fired its engines for a landing burn and the call came that it had splashed down in the Indian Ocean, just north of Australia, the relief in the room was audible.

The flight was the fourth attempt at what SpaceX wants to become routine. In April 2023 the first Starship exploded about four minutes in, before its two stages could separate. In November the stages separated and then both blew up. In March of this year the ship reached space and was lost during reentry, about forty-nine minutes into the mission. Each test went further than the one before, which is the pattern of this programme: the failures are expected, and the distance between them is the progress. What made Thursday different was that nothing was lost at all, and Elon Musk, the company’s founder, posted, in his usual arithmetic: ‘Despite loss of many tiles and a damaged flap, Starship made it all the way to a soft landing in the ocean!’

The vehicle is about 120 metres tall, powered by thirty-three Raptor engines, and designed to carry more than a hundred tonnes into orbit and, eventually, people to the Moon and Mars. NASA has bet part of its Artemis programme on it, as the lander that will take astronauts down to the lunar surface, and that contract gives this strange, ungainly test sequence a deadline and a purpose. For now the open problem is the heat shield: the flap damage and the lost tiles are a reminder that returning from orbit is still the hardest thing a spacecraft does, and the company’s plan to refuel two Starships in orbit, then land one on the Moon, depends on solving it. Thursday proved the giant can come back. The next flights will have to prove it can come back cleanly, again and again, until a soft landing in the ocean stops being news.